Mucocutaneous herpes simplex: IV: 5 mg/kg/dose every 8 hours x 5-10 days.   
Encephalitis: 10mg/kg/dose IV every 8 hours.   
Primary HSV infection-genital (Oral therapy): 200mg every 4 hours while awake (5 times/day) or 400mg orally three times daily for 10 days.  
Recurrent genital: 400mg orally three times daily for  5 days. 
Herpes Zoster: 800mg orally every 4 hours while awake (5 times/ day)  for  7 days. If severe give 10-12 mg/kg IV every 8 hours x 7-14 days.   
Chronic suppression (genital herpes): 400mg orally twice daily.  

Genital herpes suppression/prophylaxis:
[>/= 10]: Usual dose
[<10 ml/min]:  200mg q12h

Herpes zoster:
[>25 ml/min]: Usual dose
[10-25]: 800mg q8h
[<10 ml/min]:  800mg q12h

[>50 ml/min]:  No change
[30-50]: 5-10mg/kg q12h
[10-30]: 5-10mg/kg q24h
[<10 ml/min]: 2.5 to 5mg/kg q24h